Once again, many thanks for the very helpful information you have given me
on hydraulics in general, and applying them to a log splitter in particular.
I now feel confident that I could go and buy the parts from Northern Tool to
make a splitter, but as more than one person mentioned, that would raise the
cost up to a significant fraction of the price of a new machine. My
intention from the beginning has been to try to scavenge or scrounge as many
parts as possible. So, a couple of followup questions:

1) I definitely see the advantages of the two-stage pumps, and if I have to
buy a new one, I probably would go that direction. However, if I scrounge up
a pump, it may not be a two stage job. I notice that, at least on NT's
website, the non-two-stage pumps tend to be rated in cubic inches rather
than gallon-per-minute. If I'm doing the math right, it looks like the cu.
in. is the output per revolution, so that if one calculates RPM x cu. in.,
and divides by cu. in / gallon, one winds up with GPM. Yes? Or have I missed
it?

2) Any specific suggestions about where to look for suitable hydraulic parts
that might be available for scrounge prices? I've checked one nearby salvage
yard, but the only cylinders they had were off of forklifts -- they were
about 5' long and had a 5' stroke, which I somehow think would be overkill
for my logsplitter! Alternately, would one of the "wholesale hydraulics" web
sites actually be that much cheaper than NT for equivalent parts? What about
an agriculture supply outfit -- would they have what I need at a cheaper
price?

3) If I find scrounge-quality parts, what are the chances of needing to
rebuild them, and what is involved in doing so? What can't be economically
rebuilt?

4) This one may be a wild goose -- one of the links that I found via the
replies I got from you all talked about a log splitter built quite some time
back; it referred to the "original design" that used an old power steering
pump as the hydraulic pump. It sounds like that worked, but produced
relatively low pressure ( 1000 psi). Any thoughts about this wild goose?

Once again, I look forward to your patient wisdom -- TIA!

Andy